NGC 7027

NGC 7027—called the Jewel Bug Nebula or Magic Carpet Nebula—is a young, dense planetary nebula about 3,000 light-years away in Cygnus. Discovered in 1878 by Édouard Stephan with an 800 mm reflector at Marseille Observatory, it ranks among the smallest known planetary nebulae and is the most thoroughly studied.

Observation

Visually, it is one of the brightest planetary nebulae. Through a 6-inch telescope at roughly 50× magnification, it looks like a fairly bright bluish star; higher magnification gives the best view.

In 1977, a small Schmidt-Cassegrain telescope at Yerkes Observatory was used to determine its precise optical position, matching photographs with radio maps. The Hubble Space Telescope has imaged it many times since 1990. Before those observations, astronomers thought NGC 7027 was a protoplanetary nebula whose central star was too cool to ionize its gas, but it is now recognized as a very early-stage planetary nebula.

Overview

The nebula is unusually small—only 0.2 by 0.1 light-years across, compared to the typical 1 light-year—and fairly young, about 600 years old. Its shape is complex: an elliptical region of ionized gas with an equatorial belt inside a massive neutral cloud, all wrapped in a translucent shroud of gas and dust. The inner structure is a prolate ellipsoidal shell containing a photodissociation region shaped like a clover leaf. Several shocks and X-ray jets puncture the inner shell, creating spike-like features.

The nebula expands at 17 kilometers per second. Its central regions emit X-rays, indicating extremely high temperatures. Faint blue concentric shells surround the ellipsoid.

The expanding halo has about three times the Sun’s mass—roughly 100 times more massive than the ionized central region. This mass loss provided key evidence that stars a few times more massive than the Sun can avoid exploding as supernovae. The nebula is rich in carbon, making it valuable for studying carbon chemistry in dense molecular material exposed to strong ultraviolet radiation.

Its spectrum shows fewer spectral lines from neutral molecules than typical planetary nebulae, because intense UV destroys those molecules. It also contains ions of very high ionization potential. In 2019, the helium hydride ion—thought to be the first molecule formed in the Universe, about 100,000 years after the Big Bang—was detected in space for the first time in NGC 7027.